Fuel Cell and Production of Fuel Cell Stack

ABSTRACT

Separators ( 5 A,  5 B,  6 ) and membrane-electrode assemblies ( 2 ) of a fuel cell stack ( 1 ) are alternately stacked in a guide box ( 40 ). The separators ( 5 A,  5 B,  6 ) each have groove-like gas paths ( 10 A,  10 B). Powder of an adhesive agent ( 7 ) is adhered in advance to the surfaces of the separators ( 5 A,  5 B,  6 ), except the gas paths ( 10 A,  10 B), through photosensitive drums ( 31 A,  31 B) to which the powder is adsorbed in a given pattern. The separators ( 5 A,  5 B,  6 ) and the membrane-electrode assemblies ( 2 ), stacked in the guide box ( 40 ), are heated and compressed by a press ( 43 ) and heaters ( 40 C) to obtain a unitized fuel cell stack ( 1 ).

FIELD OF THE INVENTION

This invention relates to a fuel cell and production of a fuel cellstack.

BACKGROUND OF THE INVENTION

JP2001-57226A, published by the Japan Patent Office in 2001, discloses afuel cell and a fuel cell stack production method employing acylindrical intermediate adapter. In this method, through-holes areformed in membrane-electrode assemblies (MEA) and separators, and themembrane-electrode assemblies (MEA) and the separators are alternatelystacked, while passing the cylindrical intermediate adapter through thethrough-holes, thereby obtaining a fuel cell. Further, after productionof multiple fuel cells, a shaft is allowed to pass through theintermediate adapters, to thereby obtain the fuel cell stack in whichthe multiple fuel cells are stacked.

JP2001-236971A, published by the Japan Patent Office in 2001 discloses amethod in which, while the MEA is formed as a sheet, a first separatorand a second separator are arranged at a given interval on the sheet,and the fuel cells are successively produced while feeding out thosesheets. In this production method, each of the sheets are fed out sothat the MEA and the first separator, and the MEA and the secondseparator are stacked, respectively, and those sheets are thermallycompressed at a given position from outside. As a result, the firstseparator and the second separator are fitted to the MEA by pressure, tothereby successively obtain the fuel cells.

JP2003-163011A, published by the Japan Patent Office in 2003, disclosesan MEA production method in which, while feeding out a film-likeelectrolyte membrane, electrode material powder is transferred in themidway from a drum to the electrolyte membrane, thereby producing theMEA.

SUMMARY OF THE INVENTION

In the production method according to JP2001-57226A, it is necessary toform the through-holes in the MEAs and the separators in advance, andthe process of forming the through-holes involves a high cost. Further,an effective area of the fuel cells is reduced due to the through-holes.

The production methods of JP2001-236971A and JP2003-163011A are designedonly for the production of unitary fuel cells, and are not applicable tothe production of the fuel cell stack. In addition, to feed out theelectrolyte membrane, a number of rollers rotating in synchronism witheach other are used in those methods, with the result that a rotationcontrol device for those rollers involves a high cost. Further, whenfeeding the electrolyte membrane by using the rollers, there is a fearof the surface of the electrolyte membrane being flawed or being adheredwith foreign matters.

It is, therefore, an object of this invention to produce a fuel cellstack at low cost.

It is another object of this invention to prevent generation of a flawor adhesion of foreign matters when feeding an electrolyte membrane in aform of a film or a sheet.

In order to achieve the above objects, this invention provides a methodof producing a fuel cell stack comprising multiple stack materialsstacked in a given order. The method comprises a process for stackingthe stack materials in the given order in a guide box throughintermediation of an adhesive to be solidified through heating, and aprocess for integrating the stack materials by heating and compressingthe stack materials stacked in the guide box.

This invention also provides an apparatus for producing a fuel cellstack comprising multiple stack materials stacked in a given order. Theapparatus comprises a guide box that stacks the stack materials in agiven order in the guide-box through intermediation of an adhesive to besolidified through heating, and a mechanism for heating and compressingthe stack materials stacked in the guide box.

Still further, this invention provides a method of producing a fuel cellhaving an electrolyte membrane being held between a pair of separators.The production method comprises a separator arrangement process forcausing the pair of separators to be opposed to each other with a givengap therebetween, and an electrolyte membrane intrusion process forcausing the electrolyte membrane to enter the gap by applying aconveyance airflow to both sides of the electrolyte membrane.

Still further, this invention provides an apparatus for producing a fuelcell having an electrolyte membrane being held between a pair ofseparators. The production method comprises a separator conveyor forcausing the pair of separators to be opposed to each other with a givengap therebetween, and a pair of conveying nozzles for causing theelectrolyte membrane to enter the gap by applying a conveyance airflowto both sides of the electrolyte membrane.

The details as well as other features and advantages of this inventionare set forth in the remainder of the specification and are shown in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic longitudinal sectional view of a fuel cell stackproducing apparatus according to this invention.

FIG. 2 is a schematic rear view of the fuel cell stack producingapparatus.

FIG. 3 is a schematic side view of the fuel cell stack producingapparatus.

FIG. 4 is a longitudinal sectional view of a main portion of a fuel cellstack produced by the fuel cell stack producing apparatus.

FIG. 5 is a schematic longitudinal sectional view of the fuel cell stackproducing apparatus, illustrating an end separator stacking operation.

FIG. 6 is a schematic longitudinal sectional view of the fuel cell stackproducing apparatus, illustrating an MEA stacking operation.

FIG. 7 is a schematic longitudinal sectional view of the fuel cell stackproducing apparatus, illustrating an intermediate separator stackingoperation.

FIG. 8 is a schematic longitudinal sectional view of the fuel cell stackproducing apparatus, illustrating a hot press.

FIG. 9 is a schematic longitudinal sectional view of a fuel cellproducing apparatus according to a second embodiment of this invention.

FIG. 10 is an enlarged view of a main portion of FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 4 of the drawings, a fuel cell stack 1 produced by afuel cell stack producing apparatus according to a first embodiment ofthis invention will be described.

The fuel cell stack 1 is provided with membrane-electrode assemblies(MEA) 2, each of which is formed by coating both sides of a solidpolymer electrolyte membrane 3 with catalyst layers 13 constituting ananode and a cathode, and further covering the catalyst layers 13 withgas diffusion layers (GDL) 4.

The solid polymer electrolyte membrane 3 is formed by a perfluoroethylene sulfonate resin film. The catalyst layers 13 are mainly formedof platinum, and are used to coat central regions of the solid polymerelectrolyte membrane 3.

The GDLs 4 are formed of a carbon cloth or a carbon paper that hasundergone a water repellency treatment, and are attached to the innersides of frames 4B. The GDLs 4 are firmly attached to the solid polymerelectrolyte membrane 3 so as to cover the catalyst layers 13 by a fixingeffect obtained by an electrolyte solution or by a partial thermaladhesion by a thermosetting adhesive. In the following description, theGDL 4 covering the anode will be referred to as anode side GDL, and theGLD 4 covering the cathode will be referred to as the cathode side GLD4.

The MEAs 2 are alternately stacked with separators 5A, 5B or 6.

The separators 6 are intermediate separators existing between the MEAs2, and the separators 5A and 5B are end separators respectively arrangedat both ends of the fuel cell stack 1.

Each intermediate separator 6 has a groove-like anode gas path 10Afacing the anode side GDL 4 of the MEA 2, and a groove-like cathode gaspath 10B facing the cathode side GDL 4 of the adjacent MEA 2. The endseparator 5A has only the anode gas path 10A, and the end separator 5Bhas only the cathode gas path 10B. The separators 5A, 5B, and 6 areformed by compression molding of a mixture of graphite powder andplastic powder through heat press using a mold, or by press molding ofan expansion graphite sheet. It is also possible to form the separators5A, 5B, and 6 of a metal material. By using a metal material, it ispossible to obtain desirable effects of reducing electrical resistance,lowering gas permeability, enhancing mechanical strength, and reducingthickness. However, since the separators are exposed to both anoxidizing atmosphere and a reducing atmosphere, it is necessary tosecure corrosion resistance by using a corrosion resistant metal orthrough a surface treatment such as metal plating. The separators 5A,5B, and 6 are fixed to the GDLs 4 by using an adhesive 7. The adhesive 7contains as a main component a thermosetting resin of phenol type orepoxy type, and the adhesion of the separators 5A, 5B, and 6 to the GDLs4 is effected through hot press.

A hydrogen-rich gas is supplied to the anode gas path 10A of theseparators 5A and 6. Air is supplied to the cathode gas path 10B of theseparators 5B and 6. Seal grooves 15 are formed in the outer peripheryof the separators 5A, 5B, and 6. Seal members 14 are arranged in theseal grooves 15. The seal members 14 are in contact with the frames 4Bof the GDLs 4, whereby gas leakage from the anode gas paths 10A and thecathode gas paths 10B is prevented.

In this way, the fuel cell stack 1 is formed by alternately stacking agiven number of MEAs 2 and intermediate separators 6 between theseparators 5A and 5B. Further, these stacked components are fastened inthe stacking direction by bolts and nuts via the end plates.

Next, an apparatus for producing the above fuel cell stack 1 will bedescribed.

Referring to FIG. 1, the fuel cell stack producing apparatus accordingto the first embodiment of this invention is composed of a stackmaterial supply unit 20 formed in a case 25, and a stack forming unit 24situated outside the case 25.

The stack material supply unit 20 is equipped with an intermediateseparator supply unit 21, an end separator supply unit 22, and an MEAsupply unit 23.

The intermediate separator supply unit 21 is equipped with a cassette21A storing intermediate separators 6. The cassette 21A is carried intothe case 25 via a slide rail through an opening formed in the rearsurface of the case 25 as shown in FIG. 2. A grip 21B for carrying-inand carrying-out is mounted to the cassette 21A. The cassette 21A has atits bottom a bearer 21D upwardly urged by a spring 21C. The intermediateseparators 6 are superimposed one upon the other on the bearer 21, andthe uppermost intermediate separator is in contact with a stopper 21Emounted to the upper portion of the cassette 21A. The intermediateseparator supply unit 21 is equipped with a send-out roller 21F forsending out the uppermost intermediate separator 6. The cassette 21A hasan opening for sending out from the cassette 21A the uppermostintermediate separator 6 as the send-out roller 21F rotates.

The intermediate separator supply unit 21 has, in front of the openingof the cassette 21A, a pair of charging rollers 30A and a pair ofphotosensitive drums 31A.

The charging roller 30A imparts positive charge to the intermediateseparator 6 sent out by the send-out roller 21F through corona dischargeaccording to high voltage power supplied from outside. The pair ofphotosensitive drums 31A are resin drums whose surfaces are coated withamorphous selenium or zinc oxide and which are respectively in contactwith charging rollers 32A. The charging rollers 32A imparts negativecharge to the photosensitive drums 31A through corona dischargeaccording to high voltage power supplied from outside.

The intermediate separator supply unit 21 is equipped with a pair oflaser oscillators 35 facing the photosensitive drums 31A. The laseroscillators 35 perform scanning in the directions of the rotation axesof the photosensitive drums 31 with laser beams passed through opticallenses. When, as scanning is performed with the laser beams, thephotosensitive drums 31 are rotated, the charge on the surface of thephotosensitive drums 31A that have undergone scanning is lost. Further,through flashing control of the laser beams, it is possible to formcharge-less portions in an arbitrary pattern on the surfaces of thephotosensitive drums 31A.

This combination of the laser oscillators 35 and the photosensitivedrums 31A is well known as a laser scanner unit. In the fuel cell stackproducing apparatus, charge-less portions are formed at positions wherethe adhesive 7 adheres except for the anode gas paths 10A and thecathode gas paths 10B.

The intermediate separator supply unit 21 is equipped with powderrollers 33A held in contact with the photosensitive drums 31A. Thepowder rollers 33A are provided with powder containers 34A storingnegatively charged thermosetting adhesive powder, and causethermosetting adhesive powder to adhere to the charge-less portions ofthe photosensitive drums 31A as these rotate. The remaining portions ofthe surfaces of the photosensitive drums 31A are negatively charged, sothat no thermosetting adhesive powder, which is also negatively charged,adheres thereto.

When the photosensitive drums 31A, to the charge-less portions of whichthermosetting adhesive powder adheres, come into contact with theintermediate separator 6, which is positively charged, the negativelycharged thermosetting adhesive powder adheres to the surface of theintermediate separator 6. In this way, thermosetting adhesive powderadheres to the surface of the intermediate separator 6 in a givenpattern. As shown in FIG. 3, to supply thermosetting adhesive powder tothe powder containers 34A, there are formed, in a side surface of thecase 25, adhesive powder supply ports 38 that can be closed.

The intermediate separator supply unit 21 conveys the intermediateseparator 6 with thermosetting adhesive powder adhering thereto by meansof a conveying belt 36A, and sends it out to the stack forming unit 24through a gap between a pair of discharge rollers 37A installed in anopening of the casing 25 facing the stack forming unit 24.

The MEA supply unit 23 is situated directly below the intermediateseparator supply unit 21. The MEA supply unit 23 is equipped with acassette 23A storing MEAs 2. The cassette 23A is of substantially thesame construction as the cassette 21A, and is equipped with a grip 23B,a spring 23C, a bearer 23D, a stopper 23E, and a send-out roller 23F.The cassette 23B is further equipped with a humidifier 26. Thehumidifier 26 vaporizes water supplied from a water intake port 26Aprovided in the rear surface of the case 25 shown in FIG. 2, andsupplies steam to the MEA 2 situated at the uppermost position in thecassette 23B, placing the MEA 2 in a desirable moistened state.

The MEA supply unit 23 sends the MEA 2 humidified by the humidifier 26to the exterior of the cassette 23B by the send-out roller 23F. The MEAsupply unit 23 has, in front of the cassette 23B, a pair of othersend-out rollers 27, and a conveying belt 28 wrapped around one send-outroller 27. The MEA 2 conveyed by the send-out rollers 27 and theconveying belt 28 is send out to the stack forming unit 24 through a gapbetween discharge rollers 37A and 37B installed in the opening of thecase 25 facing the stack forming unit 24.

The end separator supply unit 22 is situated directly below the MEAsupply unit 23. The construction of the end separator supply unit 22 isthe same as that of the intermediate separator supply unit 21. Thus, ithas a cassette 22A equipped with a grip 22B, a spring 22C, a bearer 22D,a stopper 22E, and a send-out roller 22F. End separators 5A and 5B arealternately stored in the cassette 22A. Further, to cause thermosettingadhesive powder to adhere to the surfaces of the end separators 5A and5B in a given pattern, the end separator supply unit 22 is equipped witha pair of charging rollers 30B, a pair of photosensitive drums 31B, apair of charging rollers 32B, a pair of laser emitters 35B, and a pairof powder rollers 33B equipped with powder containers 34B. Of thesecomponents provided in pairs, those situated on the upper side are usedfor the end separators 5B, and those situated on the lower side are usedfor the end separators 5A.

The end separator supply unit 22 is equipped with a conveying belt 36Bfor sending out end separators 5A and 5B with thermosetting adhesivepowder adhering thereto.

The end separator 5A or 5B conveyed by the conveying belt 36B is sentout to the stack forming unit 24 through a gap between a pair ofdischarge rollers 37B installed in the opening of the case 25 facing thestack forming unit 24. In the following description, the intermediateseparator 6, the MEA 2, and the end separators 5A and 6B sent out fromthe opening of the case 25 will be generally referred to as the stackmaterials.

The stack forming unit 24 is equipped with a guide box 40 in which thestack materials sent out of the case 25 in a given order are stacked inthe stated order, an ascent/descent table 41 caused to ascend anddescend by an ascent/descent device 42 provided at the bottom of theguide box 40, and a press 43 which, when the amount of stack materialsin the guide box 40 reaches a given amount, cooperates with theascent/descent table 41 to exert a compressive force on the stackmaterials.

The guide box 40 is composed of a positioning protrusion 40A adapted toabut the leading edge of a stack material sent out of the case 25 toeffect positioning thereon, a box portion 40B with a rectangularhorizontal section having the positioning protrusion 40A as one sidethereof, and heaters 40C provided in the box portion 40B. The stackmaterials, whose leading edges abut the positioning protrusion 40A, aresequentially stacked within the box portion 40B, and are compressed bythe press 43 while being heated by the heaters 40C to be therebyunitized.

At the initial stage of the stacking process, the ascent/descent table41 is at the raised position, and, as the stacking of the stackmaterials proceeds, is lowered each time by a distance corresponding tothe thickness of a stack material to be controlled so as to maintain theupper end of the stack materials stacked constantly at the same height.The ascent/descent device 42 is composed of an ascent/descent rod 42Bsupporting the ascent/descent table 41, a rack 42A integrated with theascent/descent rod 42B, a pinion 42C in mesh with the rack 42A, and anelectric motor 42D adapted to rotate the pinion 42C and mounted to astand 42E. When the electric motor 42D rotates the pinion 42C, the rack42A in mesh with the pinion 42C makes a relative displacement in avertical direction together with the ascent/descent rod 42B with respectto the stand 42E, with the result that the ascent/descent table 41ascends or descends. As the ascent/descent device 42, it is alsopossible to use a screw type ascent/descent mechanism or anascent/descent mechanism using a linear cylinder.

The press 43 is equipped with a press head 43B adapted to ascend anddescend as an air cylinder 43A expands and contracts. The press head 43Bis equipped with a rectangular pressing surface to be fitted into theinterior of the guide box 40.

The fuel cell stack 1 of which the stacking has been completed by thepress head 43B and the heaters 43C is extracted from the guide box 40through ascent operation of the ascent/descent table 41. In thisprocess, in order that the raised fuel cell stack 1 and the press head43B may not interfere with each other, the ascent position of the presshead 43B is set and, further, the stroke distance is set taking intoconsideration the compressed position of the stacked body.

Next, with reference to FIGS. 5 through 8, a fuel cell stack productionprocess by the fuel cell stack producing apparatus will be described.Prior to the production process, intermediate separators 6, MEAs 2, andend separators 5A and 5B are previously stored in the cassettes 21Athrough 23A, and the charging rollers 30A, 30B, 31A, and 31B, andthermosetting adhesive powder are previously charged positively ornegatively. In the stack forming unit 24, the ascent/descent table 41and the press head 43B are both held at the raised position. The sealmembers 14 are previously fitted into the seal grooves 15 of therespective stack materials. In the MEA supply unit 22, the MEA 2 isappropriately humidified by the humidifiers 26.

Referring to FIG. 5, the fuel cell stack producing apparatus firstoperates the end separator supply unit 22, and operates the send-outroller 22F to send out the end separator 5B to the position between thepair of charging rollers 30B, positively charging the surface of the endseparator 6B by the charging roller 30B. On the other hand, at thephotosensitive drums 31B, thermosetting adhesive powder is caused toadhere to the surfaces of the drums in a given pattern by the chargingrollers 32B, the laser emitters 35B, and the powder rollers 33B.

Here, as shown in FIG. 4, the surface of the end separator 5B bonded tothe MEA 2 is the upper surface only. Thus, regarding the end separator5B, the end separator supply unit 22 operates, of the charging rollers30B and 32B, the photosensitive drums 31B, the powder rollers 33B, andthe laser emitters 35B, provided in pairs, only those situated on theupper side, causing thermosetting adhesive powder to adhere solely tothe upper surface of the end separator 5B. Here, it is to a given regionof the upper surface of the end separator 5B surrounded by the sealgroove 15, exclusive of the cathode gas path 10B, that the thermosettingadhesive powder is caused to adhere.

After thermosetting adhesive powder has been thus caused to adhere tothe given portions of the upper surface and lower surface thereof, theend separator 5B sent out from between the pair of photosensitive drums31B is conveyed by the conveying belt 36B, and sent out to a positionabove the ascent/descent table 41 in the guide box 40 of the stackforming unit 24 through the gap between the pair of discharge rollers37B installed in the opening of the case 25. At this time, thepositioning protrusion 40A abuts the leading edge of the end separator5B to effect positioning on the end separator 5B.

When the end separator 5B is placed on the ascent/descent table 41, theascent/descent device 42 lowers the ascent/descent table 41 by adistance corresponding to the thickness of the end separator 5B. As aresult, the upper surface of the end separator 5B is supported at thesame height as the upper surface of the ascent/descent table 41 shown inthe figure.

Referring to FIG. 6, the fuel cell stack producing apparatus thenoperates the MEA supply unit 23, and operates the send-out roller 23F tosend the uppermost MEA 2 in the cassette 23B to the exterior of thecassette 23B. Further, the pair of send-out rollers 27 and the conveyingbelt 28 are operated to send out the MEA 2 to a position above the endseparator 5B in the guide box 40 through the gap between the dischargerollers 37A and 37B installed in the opening of the case 25. At thistime, the positioning protrusion 40A abuts the leading edge of the MEA 2to effect positioning on the MEA 2.

When the MEA 2 is placed on the end separator 5B, the ascent/descentdevice 42 lowers the ascent/descent table 41 by a distance correspondingto the thickness of the MEA 2. As a result, the upper surface of the MEA2 is supported at the same height as the upper surface of the endseparator 5B shown in the figure.

Referring to FIG. 7, the fuel cell stack producing apparatus thenoperates the intermediate separator supply unit 21, and operates thesend-out roller 21F to send out the uppermost intermediate separator 6in the cassette 21B to the position between the pair of charging rollers30A, positively charging the surface of the intermediate separator 6 bythe charging roller 30A. On the other hand, at the photosensitive drums31A, thermosetting adhesive powder is caused to adhere to the surfacesof the drums in a given pattern by the charging rollers 32A, the laseremitters 35A, and the powder rollers 33A. As shown in FIG. 4, both theupper surface and the lower surface of the intermediate separator 6 arebonded to MEAs 2. Thus, both the upper surface and the lower surface ofthe intermediate separator 6 are positively charged, and thermosettingadhesive powder is caused to adhere to both of the pair ofphotosensitive drums 31A.

As a result, regarding the intermediate separator 6 sent out from thepair of photosensitive drums 31A, thermosetting adhesive powder iscaused to adhere to a given region surrounded by the seal groove 15 ofthe upper surface, exclusive of the cathode gas path 10B, and to a givenregion surrounded by the seal groove 15 of the lower surface, exclusiveof the anode gas path 10A.

After thermosetting adhesive powder has been thus caused to adhere tothe given portions of the upper surface and lower surface thereof, theintermediate separator 6 sent out from between the pair ofphotosensitive drums 31A is conveyed by the conveying belt 36A, and sentout to a position above the MEA 2 in the guide box 40 of the stackforming unit 24 through the gap between the pair of discharge rollers37A installed in the opening of the case 25. At this time, thepositioning protrusion 40A abuts the leading edge of the intermediateseparator 6 to effect positioning on the intermediate separator 6.

When the intermediate separator 6 is placed on the MEA 2, theascent/descent device 42 lowers the ascent/descent table 41 by adistance corresponding to the thickness of the intermediate separator 6.As a result, the upper surface of the intermediate separator 6 issupported at the same height as the upper surface of the MEA 2 shown inthe figure.

Thereafter, the fuel cell stack producing apparatus alternately executesthe operation of the MEA supply unit 23 shown in FIG. 6 and theoperation of the intermediate separator supply unit 21 shown in FIG. 7 agiven number of times to alternately layer MEAs 2 and intermediateseparators 6 in the guide box 40. Each time one of these stack materialsis stacked, the ascent/descent device 42 lowers the ascent/descent table41 by a distance corresponding to the thickness of the stack material.

When the stacking of the MEAs 2 and the intermediate separators 6,effected a given number of times, is completed, the fuel cell stackproducing apparatus operates the end separator supply unit 22 again. Atthis point in time, the end separator 5A is accommodated in the cassette22A at the uppermost position. The fuel cell stack producing apparatusoperates the send-out roller 22F, and sends out the end separator 5A tothe position between the pair of charging rollers 30B, positivelycharging the surface of the end separator 5A by the charging rollers30B.

At the photosensitive drums 31B, the charging rollers 32B, the laseremitters 35B, and the powder rollers 33B cooperate to causethermosetting adhesive powder to adhere to the surfaces of the drum in agiven pattern. As shown in FIG. 4, the surface of the end separator 5Abonded to an MEA 2 is the lower surface only. Thus, regarding the endseparator 5B, the end separator supply unit 22 operates, of the chargingrollers 30B and 32B, the photosensitive drums 31B, the powder rollers33B, and the laser emitters 35B, provided in pairs, only thoseapparatuses situated on the lower side, causing thermosetting adhesivepowder to adhere solely to the lower surface of the end separator 5A.Here, it is to a given region of the lower surface of the end separator5A surrounded by the seal groove 15 of the lower surface, exclusive ofthe anode gas path 10A, that the thermosetting adhesive powder is causedto adhere.

The end separator 5A with thermosetting adhesive powder thus adhering tothe given portion of the lower surface thereof is sent out through thegap between the pair of photosensitive drums 31B, and is conveyed by theconveying belt 36B before being sent out to a position above the MEA 2in the guide box 40 through the gap between the pair of dischargerollers 37B.

Referring to FIG. 8, when all the stack materials have been stacked, thefuel cell stack producing apparatus turns on the heaters 40C to heat thestack materials in the guide box 40. When the stack materials havereached a given temperature, the air cylinder 43A is expanded, and thepress head 43B is lowered to compress the stacked body.

As a result of this thermal compression, the thermosetting adhesivepowder stacked between the stacked bodies is cured, and bonds thestacked bodies to each other, thereby forming a unitized fuel cell stack1.

After that, the fuel cell stack producing apparatus contracts the aircylinder 43A to restore the press head 43B to the raised position and,at the same time, drives the ascent/descent device 42 to raise theascent/descent table 41 to a position above the guide box 40. The fuelcell stack 1 raised to the position above the guide box 40 is removedfrom the stack forming unit 24, and is fastened together in the stackingdirection in a device prepared as another unit by using end plates,bolts, and nuts.

The fuel cell stack producing apparatus repeatedly executes the aboveoperation, thereby successively preparing fuel cell stacks 1.

While the above embodiment employs thermosetting adhesive powder for thebonding of the stack materials to each other, it is also possible to usea thermoplastic adhesive instead of thermosetting adhesive powder.

To enhance the adsorbing force of the photosensitive drums 31, it isalso possible to mix magnetic particles called carriers into thethermosetting adhesive powder. However, depending on the material of theseparators 5A, 5B, and 6, there is a possibility of the magneticparticles generating electric erosion. Thus, it depends on the materialof the separators 5A, 5B, and 6 whether magnetic particles are to bemixed or not.

Instead of storing in the cassette 23A an MEA 2 in which a solid polymerelectrolyte membrane 3 and a GLD 4 are integrated beforehand, it is alsopossible to individually supply these components to the guide box 40from different cassettes, integrating them through thermal compressionat the stack forming unit 24.

While solely the anode gas paths 10A and/or the cathode gas paths 10Bare formed in the separators 5A, 5B, and 6, it is also possible to useseparators in which coolant paths, and humidifying water paths areformed.

According to this fuel cell stack producing apparatus, it is possible toproduce the fuel cell stack 1 at low cost while effecting positioningaccurately on the stack materials by the guide box 40.

The contents of Japanese Patent Application No. 2004-150157, filed onMay 20, 2004, will be incorporated herein by reference.

Next, a second embodiment of this invention will be described.

Referring to FIG. 9, a fuel cell producing apparatus according to thisembodiment assembles a fuel cell by integrating with each other anelectrolyte membrane 105, a pair of separators 120, and a pair of gasdiffusion layers (GDL) 121 coated with catalyst layers.

The fuel cell producing apparatus is equipped with a pair of subassembly lines 101A and 101B for integrating separators 120 and GDLs 121into separator/GDL assemblies 102, an electrolyte membrane supply unit104 for supplying an electrolyte membrane 104 between the pair ofseparator/GDL assemblies 102, and an integration unit 103 for holdingthe electrolyte membrane 104 between the pair of separator/GDLassemblies 102 and integrating them with each other.

One of the sub lines 101A and 101B assembles the anode sideseparator/GDL assembly 102 of a fuel cell, and the other sub lineassembles the cathode side separator/GDL assembly 102 of the fuel cell.

The sub lines 101A and 101B are respectively equipped with separatorconveyors 118. By performing processing on the separators 120 conveyedby the separator conveyors 118 at GDL bonding stages 116 and sealincorporating stages 117, the separator/GDL assemblies 102 are produced.Further, the separator conveyors 118 convey the completed separator/GDLassemblies 102 to the integration unit 103. Separators 120 are suppliedto the separator conveyors 118 at fixed intervals.

The separator conveyors 118 are equipped with a retaining structure forretaining the separators 120 at given positions. In a possible retainingstructure, grooves are formed in the front and rear side surfaces of theseparators 120, and claws adapted to be engaged with these grooves areprovided on the separator conveyors 118. In this case, the supply of theseparators 120 to the separator conveyors 118 is effected by sliding theseparators 120 from the sides toward the centers of the separatorconveyors 118 while causing the claws of the separator conveyors 118 toenter the grooves of the separators 120. The removal of the completedfuel cell from the separator conveyors 118 is effected by sliding theseparators 120 toward the sides of the separator conveyors 118.

It should be noted that FIG. 9 is a conceptual depiction of the fuelcell producing apparatus, and does not show the physical dimensions ofthe components thereof. For example, the radius of the bent portions ofthe separator conveyors 118 is much larger than the one as depicted inthe drawing. Further, the bending angle is not restricted to 180degrees.

The sub lines 101A and 101B are respectively equipped with jigs 122 atthe GDL bonding stages 116 and the seal incorporating stages 117. Thejigs 122 of the GDL bonding stages 116 grasp the GDLs 121, and bond theGDLs 121 to the separators 120 being conveyed by the separator conveyors118. Adhesive is applied in advance to the surfaces of the separators120 to be bonded to the GDLs 121, and, as a result of this operation,the separators 120 and the GDLs 121 are integrated. On the other hand,the surfaces of the GDLs 121 facing the jigs 122 are coated in advancethrough application, etc. with an electrolyte containing a catalystconstituting the anodes or cathodes.

The jigs 122 of the seal incorporating stages 117 grasp seal members123. Adhesive is applied to the seal members 123 in advance. The jigs122, situated on the outer side of the GDLs 121, bond the seal members123 to the separators 120 being conveyed by the separator conveyors 118.

The separator conveyors 118 convey a pair of separator/GDL assemblies102, thus assembled in the sub lines 101A and 101B, to the integrationunit 103 in a state in which they face each other.

On the other hand, the electrolyte membrane supply unit 104 is equippedwith a roll 107 of an electrolyte membrane 105, a pair of conveyingnozzles 109A for sending out the electrolyte membrane 105 from the roll107 to the integration unit 103, a pair of rectifying plates 109B, asuction device 110, and a separation nozzle 108. The roll 107 is rotatedby a servomotor.

The electrolyte membrane 105 is formed of a solid polymer electrolytemembrane, and is supplied to the fuel cell producing apparatus as theroll 107, with its surface being protected by a protective film 106. Theprotective film 106 prevents occurrence of problems due to coming intocontact with each other of portions of the electrolyte membrane 105 whenthe electrolyte membrane 105 is rolled in a roll-shape, and serves toprevent a humidity deterioration of the electrolyte membrane 105 duringconveyance or storage.

The pair of conveying nozzles 109A blow, against both surfaces of theelectrolyte membrane 105 drawn out of the roll 107, conveyance airflowsfor guiding the electrolyte membrane 105 toward the integration unit103. The pair of rectifying plates 109B rectify the conveyance airflowstoward the integration unit 103. The suction device 110 sucks theconveyance airflows passed through the integration unit 103 togetherwith the electrolyte membrane 105. As a result, the electrolyte membrane105 is pulled under an appropriate tension to enhance the conveyancefunction for the electrolyte membrane 105, and the electrolyte membrane105 is prevented from generating wrinkles or slack, maintaining theelectrolyte membrane 105 in a desirable planar configuration.

By properly controlling the humidity of the conveyance airflows blownfrom the conveying nozzles 109A, it is possible to supply theelectrolyte membrane 105 to the integration unit 103 while maintainingit to have a desirable moisture content.

The separation nozzle 108 ejects a removal airflow toward the interfacebetween the electrolyte membrane 105 and the protective film 106 sentout from the roll 7 by the rotation of the servo motor and the airflowsof the conveying nozzles 109A, and separates the protective film 106from the electrolyte membrane 105. To facilitate intrusion of theprotective film removal airflow into the interface between theelectrolyte membrane 105 and the protective film 106, the forward end ofthe separation nozzle 108 is set so as to be directed toward the curvedportion of the roll 7. Preferably, proper humidity control is alsoperformed on the protective film removal airflow to supply a highquality electrolyte membrane 105 to the integration unit 103.

As shown in the drawing, the protective film removal airflow ejectedfrom the separation nozzle 108 is in a direction opposite to thedirection in which the electrolyte membrane 105 is sent out. Thus, theprotective film removal airflow imparts an appropriate tension to theelectrolyte membrane 105 sent out toward the integration unit 103,thereby preventing generation of slack.

In the above-described construction, the electrolyte membrane supplyunit 104 gradually feeds the electrolyte membrane 105 from the roll 7toward the integration unit 103. During the operation of the integrationunit 103, the electrolyte membrane supply unit 104 does not feed theelectrolyte membrane 105. Thus, the feeding of the electrolyte membrane105 is effected intermittently in conformity with the operation of theintegration unit 103. Also regarding the pair of separator conveyors118, the conveyance of the separators 120 is not performed during theoperations of the GDL bonding stages 116, the seal incorporating stages117, and the integration unit 103. In view of this, the operations ofthe GDL bonding stages 116, the seal incorporating stages 117, and theintegration unit 103 are performed in synchronism with each other.

The integration unit 103 bonds the separator/GDL assemblies 102 conveyedby the pair of separator conveyors 118, to given positions of theelectrolyte membrane 105 conveyed therebetween. For this purpose, theintegration unit 103 is equipped with a press-fitting jig forpress-fitting the separator/GDL assemblies 102 to the electrolytemembrane 105 and a cutter for cutting the electrolyte membrane 105.

After causing the electrolyte membrane 105 to enter the gap between thepair of separator/GDL assemblies 102 by the electrolyte membrane supplyunit 104, the integration unit 103 drives the press-fitting jig topress-fit the pair of separator/GDL assemblies 102 to the electrolytemembrane 105. Further, the cutter is driven to cut the electrolytemembrane 105 between the rectifying plates 109B and the integration unit103. The surfaces of the GDLs 121 are coated with electrolyte, and theelectrolyte is brought into close contact with the bonding surfaces ofthe GDL 121 and the electrolyte membrane 105 without leaving any gap bythe pressing force of the press-fitting jig, integrating theseparator/GDL assemblies 102 with the electrolyte membrane 105. It isalso desirable to provide a heating device along with the press-fittingjig.

In this fuel cell producing apparatus, a pair of separator/GDLassemblies 102 are produced synchronously in the sub lines 101A and101B, and are conveyed synchronously to the integration unit 103 by theseparator conveyors 118. The feeding of the electrolyte membrane 105 bythe electrolyte membrane supply unit 104 is effected in synchronism withthe conveyance of the separator/GDL assemblies 102 by the separatorconveyors 118. Thus, the electrolyte membrane supply unit 104alternately repeats the feeding of the electrolyte membrane 105 for onespan and the standby during the processing at the GDL bonding stages116, the seal incorporating stages 117, and the integration unit 103.

The electrolyte membrane supply unit 104 on standby stops the servomotor driving the roll 7, and retains the electrolyte membrane 105, withits leading edge slightly protruding toward the integration unit 103from between the rectifying plates 9B, by the conveyance airflows blownout of the conveying nozzles 9A. When feeding the electrolyte membrane105, the roll 7 is rotated by the servomotor. Then, the electrolytemembrane 105 is fed to the integration unit 103 while maintaining agiven tension due to the conveying nozzles 9A and the suction device110. Preferably, the electrolyte membrane 105 is not fed for one span atone time, but is intermittently fed between the separator/GDL assemblies102. The electrolyte membrane 105 fed between the separator/GDLassemblies 102 is maintained in a non-contact state with respect to theseparator/GDL assemblies 102 on both sides by the conveyance airflowsblown out of the conveying nozzles 9A until the jig press-fits theseparator/GDL assemblies 102.

After the total intrusion of the electrolyte membrane 105 into the gapbetween the separator/GDL assemblies 102 as shown in FIG. 10, the jigpress-fits the separator/GDL assemblies 102 to the electrolyte membrane105.

By repeating the above process, fuel cells are completed successively.The completed fuel cells are successively conveyed to a place forstorage.

While in this embodiment the electrolyte membrane 105 is held betweenthe separator/GDL assemblies 102, this invention is also applicable to acase in which the electrolyte membrane 105 is held solely between thepair of GDLs 121, with the separators 120 being excluded.

As described above, in this fuel cell producing apparatus, theelectrolyte membrane 105 is fed by the conveyance airflows ejected fromthe conveying nozzles 109A, so that it is possible to prevent generationof a flaw on the electrolyte membrane 105 and adhesion of foreignmatters thereto. Further, the conveyance airflows impart an appropriatetension to the electrolyte membrane 105 being fed, making it possible toprevent generation of wrinkles and slack in the electrolyte membrane105. Thus, it is possible to supply the electrolyte membrane 105 to theintegration unit 103 in a desirable state.

The contents of Japanese Patent Application No. 2003-391044 with afiling date of Nov. 20, 2003, are herein incorporated by reference.

Although the invention has been described above by reference to certainembodiments of the invention, the invention is not limited to theembodiments described above. Modifications and variations of theembodiments described above will occur to those skilled in the art,within the scope of the claims.

FIELD OF THE INDUSTRIAL APPLICABILITY

As described above, according to this invention, the stack materials arestacked by using a guide box, so that it is possible to effectpositioning accurately on the stack materials with a simpleconstruction. Further, it is possible to produce a fuel cell stack atlow cost. This invention provides a desirable effect especially whenapplied to the production of a solid polymer type fuel cell stack.

The embodiments of this invention in which an exclusive property orprivilege is claimed are defined as follows:

1-19. (canceled)
 20. A method of producing a fuel cell stack comprising multiple stack materials stacked in a given order, the production method comprising: a process for stacking the stack materials in the given order in a guide box through intermediation of an adhesive to be solidified through heating; and a process for integrating the stack materials by heating and compressing the stack materials stacked in the guide box.
 21. The production method as defined in claim 20, wherein the multiple stack materials comprise a membrane-electrode assembly which causes a power generating reaction in response to gas supply, and separators having gas paths formed thereon, for supplying the gas to the membrane-electrode assembly.
 22. The production method as defined in claim 21, wherein the process for stacking comprises a process for holding, between the separators to surfaces of which the adhesive is applied, the membrane-electrode assembly to which no adhesive is applied.
 23. The production method as defined in claim 22, further comprising a process for humidifying the membrane-electrode assembly.
 24. The production method as defined in claim 22, further comprising a powder adhesion process for causing electrically charged powder of the adhesive to adhere to the surfaces of the separators, which are electrically charged in an opposite polarity.
 25. The production method as defined in claim 24, wherein the powder adhesion process further comprises a process for causing the powder of the adhesive to adhere to the surfaces of the separators via a photosensitive drum adsorbing the powder of the adhesive thereon in a given charging pattern.
 26. The production method as defined in claim 22, wherein the separators comprise an intermediate separator having the gas paths formed on both sides, and end separators having the gas paths formed only one side thereof, and wherein the process for stacking comprises a process for initially stacking the end separators in the guide box and a process for finally stacking the end separators in the guide box.
 27. The production method as defined in claim 20, wherein the process for stacking further comprises a process for lowering a support position for the stack materials stacked in the guide box in correspondence with an increase in thickness of the stack materials stacked in the guide box.
 28. An apparatus for producing a fuel cell stack comprising multiple stack materials stacked in a given order, the apparatus comprising: a guide box that stacks the stack materials in the given order through intermediation of an adhesive to be solidified through heating; and a mechanism that heats and compresses the stack materials stacked in the guide box.
 29. The producing apparatus as defined in claim 28, further comprising a stack material supply unit that alternately supplies the stack materials to surfaces of which the adhesive is applied and the stack material to a surface of which no adhesive is applied, to the guide box.
 30. A method of producing a fuel cell having an electrolyte membrane being held between a pair of separators, the method comprising: a separator arrangement process for causing the pair of separators to be opposed to each other with a given gap therebetween; and an electrolyte membrane intrusion process for causing the electrolyte membrane to enter the gap by applying a conveyance airflow to both sides of the electrolyte membrane.
 31. The production method as defined in claim 30, wherein the fuel cell comprises a gas diffusion layer between the separators and the electrolyte membrane, the production method further comprising a process for fixing the gas diffusion layer to each separator prior to an execution of the separator arrangement process.
 32. The production method as defined in claim 30, further comprising a process for sucking the electrolyte membrane having entered the gap between the pair of separators together with the conveyance airflow.
 33. The production method as defined in claim 30, further comprising a process for rectifying the conveyance airflow.
 34. The production method as defined in claim 30, wherein the electrolyte membrane intrusion process comprises a process for causing the electrolyte membrane to enter the gap intermittently.
 35. The production method as defined in claim 30, further comprising a process for adjusting the conveyance airflow to a given humidity.
 36. The production method as defined in claim 30, wherein the electrolyte membrane is provided in such a state that the electrolyte membrane is covered with a protective film, the production method further comprising a process for separating the protective film from the electrolyte membrane by using an airflow.
 37. The production method as defined in claim 36, wherein the electrolyte membrane is provided as a roll, and wherein the electrolyte membrane intrusion process comprises a process for drawing the electrolyte membrane out of the roll while rotating the roll.
 38. An apparatus for producing a fuel cell having an electrolyte membrane being held between a pair of separators, the apparatus comprising: a separator conveyor for causing the pair of separators to be opposed to each other with a given gap therebetween; and a pair of conveying nozzles for causing the electrolyte membrane to enter the gap by applying a conveyance airflow to both sides of the electrolyte membrane. 